Department of Crop and Forest Sciences, University of Lleida, and Centre UdL-IRTA, Alcalde Rovira Roure, 191, 25198 Lleida, Catalonia, Spain.
J Exp Bot. 2012 Jan;63(1):69-89. doi: 10.1093/jxb/err230. Epub 2011 Sep 13.
The duration of pre-anthesis developmental phases is of interest in breeding for improved adaptation and yield potential in temperate cereals. Yet despite numerous studies on the genetic control of anthesis (flowering) time and floral initiation, little is known about the genetic control of other pre-anthesis phases. Furthermore, little is known about the effect that changes in the duration of pre-anthesis phases could have on traits related to leaf appearance and tillering, or dry matter accumulation before terminal spikelet initiation (TS). The genetic control of the leaf and spikelet initiation phase (LS; from sowing to TS), the stem elongation phase (SE; from TS to anthesis), and, within the latter, from TS to flag leaf appearance and from then to anthesis, was studied in two doubled-haploid, mapping bread wheat populations, Cranbrook × Halberd and CD87 × Katepwa, in two field experiments (ACT and NSW, Australia). The lengths of phases were estimated from measurements of both TS and the onset of stem elongation. Dry weight per plant before TS, rate of leaf appearance, tillering rate, maximum number of tillers and number of leaves, and dry weight per plant at TS were also estimated in the Cranbrook × Halberd population. More genomic regions were identified for the length of the different pre-anthesis phases than for total time to anthesis. Although overall genetic correlations between LS and SE were significant and positive, independent genetic variability between LS and SE, and several quantitative trait loci (QTLs) with different effects on both phases were found in the two populations. Several of these QTLs (which did not seem to coincide with reported major genes) could be of interest for breeding purposes since they were only significant for either LS or SE. There was no relationship between LS and the rate of leaf appearance. LS was strongly and positively correlated with dry weight at TS but only slightly negatively correlated with early vigour (dry weight before TS). Despite significant genetic correlations between LS and some tillering traits, shortening LS so as to lengthen SE without modifying total time to anthesis would not necessarily reduce tillering capacity, as QTLs for tillering traits did not coincide with those QTLs significant only for LS or SE. Therefore, the study of different pre-anthesis phases is relevant for a better understanding of genetic factors regulating developmental time and may offer new tools for fine-tuning it in breeding for both adaptability and yield potential.
在温带谷物的改良适应性和产量潜力的培育中，前开花期发育阶段的持续时间是一个很有趣的研究方向。尽管已经有许多关于开花时间和花起始的遗传控制的研究，但对于其他前开花期阶段的遗传控制却知之甚少。此外，对于前开花期阶段持续时间的变化可能对与叶片出现和分蘖相关的性状或终端小穗起始 (TS) 前的干物质积累有什么影响，人们也知之甚少。从播种到 TS 的叶片和小穗起始阶段 (LS)、茎伸长阶段 (SE)（从 TS 到开花），以及后者中的从 TS 到旗叶出现和从那时到开花的阶段，在两个双单倍体作图小麦群体 Cranbrook×Halberd 和 CD87×Katepwa 中进行了研究，这两个群体在两个田间试验（ACT 和新南威尔士州，澳大利亚）中进行。从 TS 和茎伸长开始的测量来估计阶段的长度。在 Cranbrook×Halberd 群体中还估计了 TS 前每株植物的干重、叶片出现率、分蘖率、最大分蘖数和叶片数以及 TS 前每株植物的干重。与开花总时间相比，不同前开花期阶段的长度鉴定出了更多的基因组区域。尽管 LS 和 SE 之间的整体遗传相关性是显著且正向的，但在两个群体中发现了 LS 和 SE 之间独立的遗传可变性和几个对两个阶段都有不同影响的数量性状位点 (QTL)。其中一些 QTL（似乎与报道的主要基因不一致）可能具有育种意义，因为它们仅对 LS 或 SE 有意义。LS 与叶片出现率之间没有关系。LS 与 TS 时的干重呈强正相关，但与早期活力（TS 前的干重）仅呈轻微负相关。尽管 LS 和一些分蘖性状之间存在显著的遗传相关性，但缩短 LS 以延长 SE 而不改变开花总时间，不一定会降低分蘖能力，因为分蘖性状的 QTL 与仅对 LS 或 SE 有意义的 QTL 不重合。因此，对不同的前开花期阶段的研究对于更好地理解调节发育时间的遗传因素是相关的，并且可能为在适应性和产量潜力的培育中对其进行微调提供新的工具。
