Agrobacterium rhizogene-mediated genetic transformation of hairy roots is an effective method to obtain secondary metabolites. In accordance with different genotypes, it is very specific and difficult to set up a stable genetic transformation system. The plumbagin is found in the roots of Plumbago auriculata L., a secondary metabolite with significant medicinal value, but the common root grows slowly, its accumulation period is lengthy (2–6 years). In this paper, we first explored the most effective A. rhizogene-mediated (A4, ATCC 15834, and LBA 9402) genetic transformation to induce hairy root of P. auriculata, and evaluated the plumbagin concentration in different root. The results showed that the leaves were soaked with bacterial solution for 25–30 min and then transferred to 1/2 MS + AS 100 µmol·L− 1 solid medium without preculture for 2-5d. After co culture, the leaves were transferred to 1/2 MS + Cef and sterilized with cefotaxime sodium. Under this scheme, all strains can induce hairy roots, with ATCC 15834 having the highest hairy root induction rate (86.78 ± 0.74%) and the earliest root emergence time (8.33 ± 0.58 d). 1-month-grown hairy root showed an increase in plumbagin content compared with the root of the same age group and 1-year-old live seedlings, with PAHR 15834 having the highest content of 38.95 mg·g− 1 DW, which was 72.13 times higher than the same age group and 3.95 times higher than that of 1-year-old live seedlings. This is an important experimental basis for further investigation of the biosynthesis mechanism of plumbagin and the feasibility of subsequent commercial production.
Evolutionary breakdown from rigorous outbreeding to self‐fertilization frequently occurs in angiosperms. Since the pollinators are not necessary, self‐compatible populations often reduce investment in floral display characteristics and pollination reward.
Primula forbesii
is a biennial herb with distribution restricted to southwest China; it was initially a self‐incompatible distylous species, but after 20 years of artificial domestication, homostyly appeared. This change in style provides an ideal material to explore the time required for plant mating systems to adapt to new environmental changes and test whether flower attraction has reduced following transitions to selfing. We did a survey in wild populations of
P. forbesii
where its seeds were originally collected 20 years ago and recorded the floral morph frequencies and morphologies. The floral morphologies, self‐incompatibility, floral scent, and pollinator visitation between distyly and homostyly were compared in greenhouse. Floral morph frequencies of wild populations did not change, while the cultivated population was inclined to L‐morph and produced homostyly. Evidence from stigma papillae and pollen size supports the hypothesis that the homostyly possibly originated from mutations of large effect genes in distylous linkage region. Transitions to self‐compatible homostyly are accompanied by smaller corolla size, lower amounts of terpenoids, especially linalool and higher amounts of fatty acid derivatives. The main pollinators in the greenhouse were short‐tongued
Apis cerana.
However, homostyly had reduced visiting frequency. The mating system of
P. forbesii
changed rapidly in just about 20 years of domestication, and our findings confirm the hypothesis that the transition to selfing is accompanied by decreased flower attraction.
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