核桃试管嫩茎生根的形态结构及激素调控研究

Histological and Hormonal Characters during the Rhizogenesis of in Vitro Walnut Shoots

以核桃品种‘新早丰’试管嫩茎为试材,对其诱导生根过程中的形态结构及相关的生长素(IAA)和脱落酸(ABA)变化进行了研究。证实诱导生根过程中核桃嫩茎不定根原基发生于形成层,特别是髓射线正对的形成层部分;根原基起始分化期为诱导第6天左右,伸长期是第10天;如果12d之后仍放在诱导培养基中,生根率下降,并且出现茎基愈伤化、茎尖变黑和叶片脱落等现象;若生根诱导10d后转入无植物生长调节剂培养基,培养5d左右可见根尖突出表皮,根系发育正常;同时与不定根形态发生相应的内源IAA和ABA的变化是根原基的发生期和伸长期,内源IAA出现高峰,内源ABA呈上升趋势,IAA/ABA值在根原基的发生前为最大,随后降低。本研究不仅从形态结构证实了二步生根法的合理性,而且从生理学角度阐述了不定根发生的IAA/ABA调控机制。

Histological characters and the modification of endogenous IAA and ABA during the rhizogene- sis of walnut shoots were investigated with in vitro cuhivar of Xinzaofeng （ Juglans regia L. ）. It was identified that the adventitious root primordia of in vitro shoot originated from the vascular cambium cells, especially, the cross areas of cambium and pith ray and they started to differentiate at the 6^th dayand lasted to the 10^th day. If the shoots were cultured in the root inducing medium for 12 days, led to not only descend of rooting rate, but also the damaged plantlets, showing black shoot tips, callus of stem base, and leaf senescent. However, if they were transferred into the medium without hormone in time, the root primordial protruded the epidermis and developed normally after 5 days culture. It was also found that when the adventitious root primordia formed and lengthened, endogenous IAA concentration reach the peak and ABA was still increasing. The rate of IAA and ABA was maximum before the adventitious root primordium forming, afterwards, it decreased. The research not only confirmed that the two steps method is reasonable for walnut rhizogenesis; but also expounded the mechanism of the hormone regulation during the induced rooting on the physiological level.