目的 探讨CD25单抗在无血缘关系造血干细胞移植（UHSCT）中对干细胞植入和移植物抗宿主病（GVHD）的作用。方法 27例UHCST中，移植后1、4d给予CD25单抗1mg/kg。结果 27例中，除1例早期死亡外，26例患者造血全部重建。17例发生急性GVHD，其中Ⅱ度以上急性GVHD6例（23％）。复发3例，严重感染3例。26例可评价患者中，19例无病生存（73％）。结论 CD25单抗在UHSCT中对保证干细胞植入和预防GVHD有肯定的作用，白血病复发并不增加。此研究为UHCST和HLA不合的造血干细胞移植提供一个可选择的途径。

Drought is a predominant cause of low yields worldwide. There is an urgent need for more water efficient cropping systems facing large water consumption of irrigated agriculture and high unproductive losses via runoff and evaporation. Identification of yield-limiting constraints in the plant–soil–atmosphere continuum are the key to improved management of plant water stress. Crop ecology provides a systematic approach for this purpose integrating soil hydrology and plant physiology into the context of crop production. We review main climate, soil and plant properties and processes that determine yield in different water-limited environments. From this analysis, management measures for cropping systems under specific drought conditions are derived. Major findings from literature analysis are as follows. (1) Unproductive water losses such as evaporation and runoff increase from continental in-season rainfall climates to storage-dependent winter rainfall climates. Highest losses occur under tropical residual moisture regimes with short intense rainy season. (2) Sites with a climatic dry season require adaptation via phenology and water saving to ensure stable yields. Intermittent droughts can be buffered via the root system, which is still largely underutilised for better stress resistance. (3) At short-term better management options such as mulching and date of seeding allow to adjust cropping systems to site constraints. Adapted cultivars can improve the synchronisation between crop water demand and soil supply. At long term, soil hydraulic and plant physiological constraints can be overcome by changing tillage systems and breeding new varieties with higher stress resistance. (4) Interactions between plant and soil, particularly in the rhizosphere, are a way towards better crop water supply. Targeted management of such plant–soil interactions is still at infancy. We conclude that understanding site-specific stress hydrology is imperative to select the most efficient measures to mitigate stress. Major progress in future can be expected from crop ecology focussing on the management of complex plant (root)–soil interactions.

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Management of crop water under drought: a review

Grain yield is a major goal for the improvement of durum wheat, particularly in drought-prone areas. In this study, the genetic basis of grain yield (GY), heading date (HD), and plant height (PH) was investigated in a durum wheat population of 249 recombinant inbred lines evaluated in 16 environments (10 rainfed and 6 irrigated) characterized by a broad range of water availability and GY (from 5.6 to 58.8 q ha−1). Among the 16 quantitative trait loci (QTL) that affected GY, two major QTL on chromosomes 2BL and 3BS showed significant effects in 8 and 7 environments, with R2 values of 21.5 and 13.8% (mean data of all 16 environments), respectively. In both cases, extensive overlap was observed between the LOD profiles of GY and PH, but not with those for HD. QTL specific for PH were identified on chromosomes 1BS, 3AL, and 7AS. Additionally, three major QTL for HD on chromosomes 2AS, 2BL, and 7BS showed limited or no effects on GY. For both PH and GY, notable epistasis between the chromosome 2BL and 3BS QTL was detected across several environments.

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Quantitative Trait Loci for Grain Yield and Adaptation of Durum Wheat (Triticum durum Desf.) Across a Wide Range of Water Availability

Drought escape is a classical adaptive mechanism which involves rapid plant development to enable the completion of the full life-cycle prior to a coming drought event. This strategy is widely used in populations of native plants, and is also applicable to cereal crops such as wheat. Early flowering time and a shorter vegetative phase can be very important for wheat production in conditions of terminal drought since this can minimise exposure to dehydration during the sensitive flowering and post-anthesis grain filling periods. A gradual shift towards early flowering has been observed over the last century of wheat breeding in countries with a Mediterranean-type climate and frequent terminal drought. This trend is predicted to continue for wheat production in the coming years in response to global climate warming. The advantage of early flowering wheat is apparent under conditions of impending terminal drought. Under favourable conditions, a short vegetative phase can result in reduced plant biomass which will limit nutrients and assimilates for high grain yield in the absence of stress. However, where the early flowering trait exists in combination with other drought tolerance mechanisms and high yield potential have been reported, early flowering provides a promising strategy for the production of advanced drought-adapted wheat cultivars.

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Early Flowering as a Drought Escape Mechanism in Plants: How Can It Aid Wheat Production?

Modern agriculture and conventional breeding and the liberal use of high inputs has resulted in the loss of genetic diversity and the stagnation of yields in cereals in less favourable areas. Increasingly landraces are being replaced by modern cultivars which are less resilient to pests, diseases and abiotic stresses and thereby losing a valuable source of germplasm for meeting the future needs of sustainable agriculture in the context of climate change. Where landraces persist there is concern that their potential is not fully realised. Much effort has gone into collecting, organising, studying and analysing landraces recently and we review the current status and potential for their improved deployment and exploitation, and incorporation of their positive qualities into new cultivars or populations for more sustainable agricultural production. In particular their potential as sources of novel disease and abiotic stress resistance genes or combination of genes if deployed appropriately, of phytonutrients accompanied with optimal micronutrient concentrations which can help alleviate aging-related and chronic diseases, and of nutrient use efficiency traits.We discuss the place of landraces in the origin of modern cereal crops and breeding of elite cereal cultivars, the importance of on-farm and ex situ diversity conservation; how modern genotyping approaches can help both conservation and exploitation; the importance of different phenotyping approaches; and whether legal issues associated with landrace marketing and utilisation need addressing. In this review of the current status and prospects for landraces of cereals in the context of sustainable agriculture, the major points are the following: (1) Landraces have very rich and complex ancestry representing variation in response to many diverse stresses and are vast resources for the development of future crops deriving many sustainable traits from their heritage. (2) There are many germplasm collections of landraces of the major cereals worldwide exhibiting much variation in valuable morphological, agronomic and biochemical traits. The germplasm has been characterised to variable degrees and in many different ways including molecular markers which can assist selection. (3) Much of this germplasm is being maintained both in long-term storage and on farm where it continues to evolve, both of which have their merits and problems. There is much concern about loss of variation, identification, description and accessibility of accessions despite international strategies for addressing these issues. (4) Developments in genotyping technologies are making the variation available in landraces ever more accessible. However, high quality, extensive and detailed, relevant and appropriate phenotyping needs to be associated with the genotyping to enable it to be exploited successfully. We also need to understand the complexity of the genetics of these desirable traits in order to develop new germplasm. (5) Nutrient use efficiency is a very important criterion for sustainability. Landrace material offers a potential source for crop improvement although these traits are highly interactive with their environment, particularly developmental stage, soil conditions and other organisms affecting roots and their environment. (6) Landraces are also a potential source of traits for improved nutrition of cereal crops, particularly antioxidants, phenolics in general, carotenoids and tocol in particular. They also have the potential to improve mineral content, particularly iron and zinc, if these traits can be successfully transferred to improved varieties. (7) Landraces have been shown to be valuable sources of resistance to pathogens and there is more to be gained from such sources. There is also potential, largely unrealised, for disease tolerance and resistance or tolerance of pest and various abiotic stresses too including to toxic environments. (8) Single gene traits are generally easily transferred from landrace germplasm to modern cultivars, but most of the desirable traits characteristic of landraces are complex and difficult to express in different genetic backgrounds. Maintaining these characteristics in heterogeneous landraces is also problematic. Breeding, selection and deployment methods appropriate to these objectives should be used rather than those used for high input intensive agriculture plant breeding. (9) Participatory plant breeding and variety selection has proven more successful than the approach used in high input breeding programmes for landrace improvement in stress-prone environments where sustainable approaches are a high priority. Despite being more complex to carry out, it not only delivers improved germplasm, but also aids uptake and communication between farmers, researchers and advisors for the benefit of all. (10) Previous seed trade legislation was designed primarily to protect trade and return royalty income to modern plant breeders with expensive programmes to fund. As the desirability of using landraces becomes more apparent to achieve greater sustainability, legislation changes are being made to facilitate this trade too. However, more changes are needed to promote the exploitation of diversity in landraces and encourage their use.

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Cereal landraces for sustainable agriculture. A review

Breeding progress in morpho-physiological, agronomical and qualitative traits of durum wheat cultivars released in Italy during the 20th century

Determinants of barley grain yield in a wide range of Mediterranean environments

The genetic gain of oats in Italy over the past 40 years was evaluated using 14 cultivars belonging to three different groups: (i) five cultivars derived from local populations at the beginning of the oat breeding in Italy; (ii) four foreign cultivars, introduced in Italy in the 1980s; (iii) five modern cultivars, selected through specific breeding programmes. The genotypes were tested for 2 years in three locations characterised by different climatic conditions and agricultural practices; furthermore in one location in Southern Italy, irrigated and rainfed plots were compared. Genetic gain was estimated equal to 3.6 g m−2 y−1 based on eight environments. The performance of the most recent cultivars was high under both irrigated and rainfed conditions, showing a good adaptation of these genotypes to both fertile and drought prone environments. Finally, yield increase in oats was found to be negatively correlated with plant height and positively correlated with test weight and seed weight.

Orazio Li Destri Nicosia

Papers

Breeding progress in morpho-physiological, agronomical and qualitative traits of durum wheat cultivars released in Italy during the 20th century

Determinants of barley grain yield in a wide range of Mediterranean environments

Genetic progress of oats in Italy