Root system size response of bzh semi-dwarf oilseed rape hybrids to different nitrogen levels in the field
Root system size response of bzh semi-dwarf oilseed rape hybrids to different nitrogen levels in the field
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DOI：
10.1093/aob/mcy197
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发表时间：
2018-11
期刊：
影响因子：
4.2
通讯作者：
A. Schierholt;Tina Tietz;G. Bienert;A. Gertz;Sebastian Miersch;H. Becker
中科院分区：
文献类型：
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作者：
A. Schierholt;Tina Tietz;G. Bienert;A. Gertz;Sebastian Miersch;H. Becker
摘要背景与目的油菜矮系与普通系杂交的半矮系杂种越来越受到人们的关注。与普通品种相比，它们具有较好的氮素吸收、氮素利用率和氮素利用效率。本研究旨在阐明这些与氮有关的效应是否可以单独用白杨茎的生长类型来解释，或者也可以用根系性状的差异来解释。方法利用根系电容量（EC）测定bzh-位点两组基因型分离的根系大小：(1)2010-2012两季双单倍体（DH）试验杂交种108个，(2)2016 - 2017两季近等基因杂交种16个。对DH试验杂交种根系EC的数量性状位点（QTL）进行了估计。体外监测幼苗根系结构参数。bzh半矮秆杂种离体根系生长表现出较高的根冠比。田间试验中，高施氮条件下根系EC高于零施氮条件。在大多数试验中，半矮秆杂交种的光合速率高于普通型杂交种，但对氮素限制的根系光合速率降低高于普通型杂交种。在近等基因杂交种中，根系EC在花末（h2 = 0.73）比花初（h2 = 0.36）具有更强的遗传力，在DH试验杂交种中具有更低的遗传力（h2 = 0.27）。在零氮施肥条件下，连锁群A06上bzh-位点基因组区域的根EC QTL显著。结论根系EC在油菜根系大小育种中是一种有意义的方法。在低氮供应条件下，半矮秆根系EC比正常类型减少得更多，同时氮效率增加，这意味着在根系中不是“越多越好”的问题，而bzh根系在缺氮时反应高度经济。
Abstract Background and Aims In oilseed rape (Brassica napus) semi-dwarf hybrid varieties from crosses between bzh dwarf and normal-type lines are of increasing interest. They have improved nitrogen (N) uptake, N-utilization and N-use efficiency compared to normal types. This study aimed to elucidate whether these N-related effects can be explained by the bzh shoot growth-type alone or also by differences in root traits. Methods Root system size was measured using root electrical capacitance (EC) in field trials with two N levels in two sets of genotypes segregating for the bzh-locus: (1) 108 doubled haploid (DH) test hybrids in two seasons, 2010–2012, and (2) 16 near-isogenic hybrids in the 2016–17 season. Quantitative trait loci (QTL) for root EC were estimated in DH test hybrids. Seedling root architecture parameters were monitored in vitro. Key Results In vitro root growth showed a higher root: shoot ratio in bzh semi-dwarf hybrids. Root EC in field trials was higher at high N supply than at zero N fertilization. In most trials semi-dwarf hybrids had higher EC than normal-type hybrids, but they reduced root EC in response to N limitation more than normal types. Root EC was more heritable at the end of flowering (h2 = 0.73) than at the beginning of flowering (h2 = 0.36) in near-isogenic hybrids and had a lower heritability in trials of DH test hybrids (h2 = 0.27). A QTL for root EC in the genomic region of the bzh-locus on linkage group A06 was significant at zero N fertilization. Conclusions Root EC proved to be a meaningful method in oilseed rape breeding programmes targeting root system size. The greater reduction of semi-dwarf root EC compared to the normal type under low N supply with simultaneous increase in N efficiency implies that in roots it is not a question of ‘the more the merrier’ and that the bzh root system reacts highly economically when N is scarce.