The yield potential ( Y p ) of a grain crop is the seed mass per unit ground area obtained under optimum growing conditions without weeds, pests and diseases. It is determined by the product of the available light energy and by the genetically determined properties: efficiency of light capture ( e i ), the efficiency of conversion of the intercepted light into biomass ( e c ) and the proportion of biomass partitioned into grain ( h ). Plant breeding brings h and e i close to their theoretical maxima, leaving e c , primarily determined by photosynthesis, as the only remaining major prospect for improving Y p . Leaf photosynthetic rate, however, is poorly correlated with yield when different genotypes of a crop species are compared. This led to the viewpoint that improvement of leaf photosynthesis has little value for improving Y p . By contrast, the many recent experiments that compare the growth of a genotype in current and future projected elevated [CO 2 ] environments show that increase in leaf photosynthesis is closely associated with similar increases in yield. Are there opportunities to achieve similar increases by genetic manipulation? Six potential routes of increasing e c by improving photosynthetic efficiency were explored, ranging from altered canopy architecture to improved regeneration of the acceptor molecule for CO 2 . Collectively, these changes could improve e c and, therefore, Y p by c . 50%. Because some changes could be achieved by transgenic technology, the time of the development of commercial cultivars could be considerably less than by conventional breeding and potentially, within 10‐15 years.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-3040.2005.01493.x

Can improvement in photosynthesis increase crop yields

This invention provides transgenic plant cells with recombinant DNA for expression of proteins that are useful for imparting enhanced agronomic trait(s) to transgenic crop plants. This invention also provides transgenic plants and progeny seed comprising the transgenic plant cells where the plants are selected for having an enhanced trait selected from the group of traits consisting of enhanced water use efficiency, enhanced cold tolerance, increased yield, enhanced nitrogen use efficiency, enhanced seed protein and enhanced seed oil. Also disclosed are methods for manufacturing transgenic seed and plants with enhanced traits.

Transgenic Plants with Enhanced Agronomic Traits

This chapter describes a procedure for Agrobacterium-mediated wheat transformation. Freshly isolated immature embryos, precultured immature embryos, or embryogenic calli are inoculated with a disarmed A. tumefaciens strain C58 (ABI) harboring the binary vector pMON18365 containing the beta-glucuronidase (GUS) gene with an intron, and a selectable marker, neomycinphosphotranferase (NPT) II gene. The inoculated explants are selected on callus induction medium with the selective agent G418 for approximately 2 wk. The resistant callus pieces that develop are then transferred onto medium with the selective agent and reduced plant growth regulators for plant regeneration and further selection. It takes approximately 2.5 to 3 mo from inoculation to the establishment of R0 plants in soil. All the transformants should be morphologically normal and set seeds. Approximately 35% of the transgenic plants have a single copy of the transgene based on data obtained from previous experiments.

Wheat ( Triticum aestivum L.)

Since the success of Agrobacterium-mediated transformation of rice in the early 1990s, significant advances in Agrobacterium-mediated transformation of monocotyledonous plant species have been achieved. Transgenic plants obtained via Agrobacterium-mediated transformation have been regenerated in more than a dozen monocotyledonous species, ranging from the most important cereal crops to ornamental plant species. Efficient transformation protocols for agronomically important cereal crops such as rice, wheat, maize, barley, and sorghum have been developed and transformation for some of these species has become routine. Many factors influencing Agrobacterium-mediated transformation of monocotyledonous plants have been investigated and elucidated. These factors include plant genotype, explant type, Agrobacterium strain, and binary vector. In addition, a wide variety of inoculation and co-culture conditions have been shown to be important for the transformation of monocots. For example, antinecrotic tr...

https://bioone.org/journals/in-vitro-cellular-and-developmental-biology---plant/volume-40/issue-1/IVP2003501/Invited-review--Factors-influencing-Agrobacterium-mediated-transformation-of-monocotyledonous/10.1079/IVP2003501.pdf

Factors influencing Agrobacterium -mediated transformation of monocotyledonous species

Two barley transformation systems, Agrobacterium-mediated and particle bombardment, were compared in terms of transformation efficiency, transgene copy number, expression, inheritance and physical structure of the transgenic loci using fluorescence in situ hybridisation (FISH). The efficiency of Agrobacterium-mediated transformation was double that obtained with particle bombardment. While 100% of the Agrobacterium-derived lines integrated between one and three copies of the transgene, 60% of the transgenic lines derived by particle bombardment integrated more than eight copies of the transgene. In most of the Agrobacterium-derived lines, the integrated T-DNA was stable and inherited as a simple Mendelian trait. Transgene silencing was frequently observed in the T1 populations of the bombardment-derived lines. The FISH technique was able to reveal additional details of the transgene integration site. For the efficient production of transgenic barley plants, with stable transgene expression and reduced silencing, the Agrobacterium-mediated method appears to offer significant advantages over particle bombardment.

A comparison of transgenic barley lines produced by particle bombardment and Agrobacterium-mediated techniques.

An Agrobacterium-mediated transformation system with glyphosate selection has been developed for the large-scale production of transgenic plants. The system uses 4-day precultured immature embryos as explants. A total of 30 vectors containing the 5-enol-pyruvylshikimate-3-phosphate synthase gene from Agrobacterium strain CP4 (aroA:CP4), which confers resistance to glyphosate, were introduced into wheat using this system. The aroA:CP4 gene served two roles in this study—selectable marker and gene of interest. More than 3,000 transgenic events were produced with an average transformation efficiency of 4.4%. The entire process from isolation of immature embryos to production of transgenic plantlets was 50–80 days. Transgenic events were evaluated over several generations based on genetic, agronomic and molecular criteria. Forty-six percent of the transgenic events fit a 3:1 segregation ratio. Molecular analysis confirmed that four of six lead transgenic events selected from Agrobacterium transformation contained a single insert and a single copy of the transgene. Stable expression of the aroA:CP4 gene was confirmed by ELISA through nine generations. A comparison of Agrobacterium-mediated transformation to a particle bombardment system demonstrated that the Agrobacterium system is reproducible, has a higher transformation efficiency with glyphosate selection and produces higher quality transgenic events in wheat. One of the lead events from this study, no. 33391, has been identified as a Roundup Ready wheat commercial candidate.

Agrobacterium-mediated large-scale transformation of wheat (Triticum aestivum L.) using glyphosate selection

Herbicide tolerant crops provide farmers access to a new weed control option of nonselective herbicide such as Roundup 1 . A wheat transgenic event 33391 was produced via Agrobacterium-mediated transformation of a donor cultivar Bobwhite wheat (Triticum aestivum L.) and was identified as a commercial candidate to develop Roundup Ready wheat 2 . The objective of this study was to assess field efficacy of the transgenic event in spring wheat production regions in North America. Transgenic event 33391 was tested in field trials at 14 locations in 1999, 13 locations in 2000, and 14 locations in 2001. All trials were split-plot designs with multiple rates of Roundup treatment. No vegetative or reproductive damage was observed with the application of 4 L ha -1 Roundup at the 3- to 5-leaf stages. No yield reduction was observed with Roundup treatment. The transgenic event with or without Roundup application yielded as high as the nontransgenic Bobwhite. These results indicate that the wheat transgenic event 33391 has at least 2x tolerance to the nonselective herbicide Roundup.

Field Efficacy Assessment of Transgenic Roundup Ready Wheat

CONTEXT
Covalent BTK inhibitors (BTKi) have transformed the management of mantle cell lymphoma (MCL), but most patients will require additional treatment. Pirtobrutinib is a highly selective, non-covalent (reversible) BTKi that inhibits both wild-type and C481-mutated BTK with equal low nM potency.


OBJECTIVE
To evaluate pirtobrutinib safety and efficacy in patients with MCL.


DESIGN
BRUIN is an ongoing multicenter phase 1/2 study (NCT03740529) of pirtobrutinib monotherapy.


SETTING
Global; community hospitals, academic medical centers.


PATIENTS
Patients with advanced B-cell malignancies.


INTERVENTIONS
Oral pirtobrutinib, phase 1 dose-escalated in a standard 3+3 design, phase 2 continuous therapy, 28-day cycles.


MAIN OUTCOME MEASURES
The primary phase 1 objective was to determine the recommended phase 2 dose (RP2D) and the primary phase 2 objective was overall response rate (ORR); secondary objectives included duration of response, progression-free survival, overall survival, safety/tolerability, and pharmacokinetics.


RESULTS
As of 27 September 2020, 323 patients (170 CLL/SLL, 61 MCL, 26 WM, 26 DLBCL, 13 MZL, 12 FL, 9 RT, and 6 other NHL) were treated on 7 dose levels (25-300mg QD). No DLTs were reported and MTD was not reached (n=323). 200mg QD was selected as the RP2D. Fatigue (20%), diarrhea (17%) and contusion (13%) were the most frequent treatment-emergent adverse events regardless of attribution or grade seen in >10% of patients. The most common adverse event of grade ≥3 was neutropenia (10%). Five (1%) patients discontinued due to treatment-related adverse events. 52 prior BTKi treated MCL patients were efficacy evaluable with an ORR of 52% (95% CI 38-66; 13 CR [25%], 14 PR [27%], 9 SD [17%]), 11 PD [21%] and 5 [10%] discontinued prior to first response assessment). Median follow-up was 6 months (0.7-18.3+). Responses were observed in 9/14 patients (64%) with prior autologous or allogeneic stem cell transplant, and 2/2 with prior CAR-T cell therapy.


CONCLUSIONS
Pirtobrutinib demonstrated promising efficacy in heavily pretreated, poor-prognosis MCL following multiple prior lines of therapy, including a covalent BTKi. Pirtobrutinib was well tolerated and exhibited a wide therapeutic index. Updated data, including approximately 60 new patients with MCL and an additional 10 months since the prior data-cut will be presented.

P1101: pirtobrutinib, a highly selective, non-covalent (reversible) btk inhibitor in previously treated mantle cell lymphoma: updated results from the phase 1/2 bruin study

C. A. Chay

Papers

Agrobacterium-mediated large-scale transformation of wheat (Triticum aestivum L.) using glyphosate selection

Field Efficacy Assessment of Transgenic Roundup Ready Wheat

P1101: pirtobrutinib, a highly selective, non-covalent (reversible) btk inhibitor in previously treated mantle cell lymphoma: updated results from the phase 1/2 bruin study