Ntawuguranayo Simeon, Zilberberg Michael, Nashef Kamal, Bonfil David J, Bainsla Naresh Kumar, Piñera-Chavez Francisco J, Reynolds Matthew Paul, Peleg Zvi, Ben-David Roi
The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel.
The Institute of Plant Sciences, Agriculture Research Organization (ARO) - Volcani Institute, Rishon LeZion, Israel.
Front Plant Sci. 2024 Jul 25;15:1388881. doi: 10.3389/fpls.2024.1388881. eCollection 2024.
Wheat grain filling processes under post-anthesis stress scenarios depend mainly on stem traits and remobilization of stem water-soluble carbohydrates (WSC).
A diverse panel of advanced semi-dwarf spring wheat lines, representing a natural variation in stem traits (WSC content, stem diameter, peduncle length, and stem wall width), was used to identify specific traits that reliably reflect the relationship between WSC and grain yield. The panel was phenotyped under various environmental conditions: well-watered, water-limited, and heat stress in Mexico, and terminal-drought in Israel.
Environmental stresses reduced grain yield (from 626 g m under well-watered to 213 g m under heat), lower internode diameter, and peduncle length. However, stem-WSC generally peaked 3-4 weeks after heading under all environmental conditions except heat (where it peaked earlier) and expressed the highest values under water-limited and terminal-drought environments. Increased investment in internode diameter and peduncle length was associated with a higher accumulation of stem WSC, which showed a positive association with yield and kernel weight. Across all environments, there were no apparent trade-offs between increased crop investment in internode diameter, peduncle length, and grain yield.
Our results showed that selecting for genotypes with higher resource investment in stem structural biomass, WSC accumulation, and remobilization could be a valuable strategy to ameliorate grain size reduction under stress without compromising grain yield potential. Furthermore, easy-to-measure proxies for WSC (stem diameter at specific internodes and length of the last internode, i.e., the peduncle) could significantly increase throughput, potentially at the breeding scale.
花后胁迫情景下的小麦籽粒灌浆过程主要取决于茎秆性状以及茎秆水溶性碳水化合物（WSC）的再转运。
使用一组多样化的先进半矮秆春小麦品系，这些品系代表了茎秆性状（WSC含量、茎直径、穗下节间长度和茎壁宽度）的自然变异，以确定能可靠反映WSC与籽粒产量之间关系的特定性状。该品系在各种环境条件下进行表型分析：墨西哥的充分供水、水分受限和热胁迫条件，以及以色列的终花期干旱条件。
环境胁迫降低了籽粒产量（从充分供水条件下的626克/平方米降至热胁迫条件下的213克/平方米）、降低了节间直径和穗下节间长度。然而，除热胁迫（其峰值出现得更早）外，在所有环境条件下，茎秆WSC通常在抽穗后3 - 4周达到峰值，并且在水分受限和终花期干旱环境下表现出最高值。节间直径和穗下节间长度的增加与茎秆WSC的更高积累相关，而茎秆WSC与产量和粒重呈正相关。在所有环境中，作物在节间直径、穗下节间长度和籽粒产量方面增加的投入之间没有明显的权衡。
我们的结果表明，选择在茎秆结构生物量、WSC积累和再转运方面具有更高资源投入的基因型，可能是一种有价值的策略，可在不影响籽粒产量潜力的情况下减轻胁迫下籽粒大小的减小。此外，WSC的易于测量的替代指标（特定节间的茎直径和最后一个节间即穗下节间的长度）可以显著提高通量，可能在育种规模上实现。
