OsGA20ox2不同长度RNAi片段对水稻株高等农艺性状的遗传效应

利用OsGA20ox2基因序列构建不同长度的RNAi片段并导入水稻，获得不同高度的矮化植株。将这些矮化植株与野生型植株回交获得B₁F₂群体，卡方检测表明B₁F₂群体矮秆植株数和高秆植株数符合3∶1比例，表现为矮秆显性的遗传规律。对矮化植株的F₅和B₁F₂群体株高、各茎节间长度和一些主要农艺性状方差分析显示, OsGA20ox2基因的RNAi能显著缩短株高和各节间长度(P<0.05)，RNAi干扰片段越长，使植株株高和节间长度缩短程度越大，可使株高降低24~42 cm，矮化22%~39%。在同一长度的RNAi干扰片段下，倒一节节间长度平均缩短与倒二节节间长度平均缩短非常相近，倒三节和倒四节节间长度平均缩短非常相近，总的缩短程度是倒四节>倒三节>倒二节>倒一节。这种近基部节间长度缩短幅度和比例较大的特点，利于提高水稻的抗倒伏能力，同时上部节间缩短幅度和比例较小，有效地保持合理株高，不使生物产量明显降低，有利于水稻的稳产和高产。OsGA20ox2基因的RNAi不影响如千粒重、结实率、穗长等其他主要农艺性状或影响很小。

Genetic Effects of Different RNA Interference Fragments from OsGA20ox2 on Plant Height and Other Agronomic Traits in Rice

In our previous study, different rice dwarf lines were obtained through rice genetic transformation using RNAi vectors harboring different fragments of OsGA20ox2 gene. In this study, B1F2 populations were produced by backcrossing between those RNAi dwarf lines and wild-type plants. The progenies of B1F2 populations segregated in a ratio of 3 dwarf plants to 1 normal height plant, indicating that dwarf trait was dominantly inherited. At the same time, plant height, the internode length and some major agronomic traits of dwarf plants of F5 and B1F2 populations were analyzed. The RNAi of OsGA20ox2 gene significantly reduced the rice plant height and the internode length. The longer the interference fragment was, the shorter the plant height and internode length were. In general, the rice plant height was reduced by 24–42 cm, dwarfing ratio was 22–39%. For the same RNAi fragment, the average shorten length of the first internode (counting from the top to bottom) was very similar to that of the second, and the third was very similar to the fourth. The dwarfing ratio of each internode showed a trend of the fourth > third > second > first section. Bottom internodes obtained a greater dwarfing ratio, which is good for improving lodging resistance of rice, and the upper internodes showed a lower dwarfing ratio that made the plant maintain a reasonable height, which helps the rice plants to remain a stable and high yield. Other major agronomic traits such as grain weight, seed setting rate, panicle length were not sig-nificantly affected by the RNAi of OsGA20ox2 gene.