Open AccessElevated auxin and reduced cytokinin contents in rootstocks improve their performance and grafting success
Author(s) -
Li Wei,
Fang Chu,
Krishnan Sanalkumar,
Chen Junmei,
Yu Hao,
Murphy Angus S.,
Merewitz Emily,
KatinGrazzini Lorenzo,
McAvoy Richard J.,
Deng Ziniu,
Zale Janice,
Li Yi
Publication year - 2017
Publication title -
plant biotechnology journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.525
H-Index - 115
eISSN - 1467-7652
pISSN - 1467-7644
DOI - 10.1111/pbi.12738
Subject(s) - rootstock , biology , auxin , cytokinin , apical dominance , transgene , grafting , botany , genetically modified crops , lateral root , arabidopsis , gene , horticulture , shoot , biochemistry , mutant , chemistry , organic chemistry , polymer
Summary Plant grafting is an important technique for horticultural and silvicultural production. However, many rootstock plants suffer from undesirable lateral bud outgrowth, low grafting success rates or poor rooting. Here, we used a root‐predominant gene promoter ( Sb UGT ) to drive the expression of a tryptophan‐2‐monooxygenase gene ( iaaM ) from Agrobacterium tumefaciens to increase auxin levels in tobacco. The transgenic plants, when used as a rootstock, displayed inhibited lateral bud outgrowth, enhanced grafting success rate and improved root initiation. However, root elongation and biomass of Sb UGT ::iaaM transgenic plants were reduced compared to those of wild‐type plants. In contrast, when we used this same promoter to drive CKX (a cytokinin degradation gene) expression, the transgenic tobacco plants displayed enhanced root elongation and biomass. We then made crosses between the Sb UGT :: CKX and Sb UGT ::iaaM transgenic plants. We observed that overexpression of the CKX gene neutralized the negative effects of auxin overproduction on root elongation. Also, the simultaneous expression of both the iaaM and CKX genes in rootstock did not disrupt normal growth and developmental patterns in wild‐type scions. Our results demonstrate that expression of both the iaaM and CKX genes predominantly in roots of rootstock inhibits lateral bud release from rootstock, improves grafting success rates and enhances root initiation and biomass.