Anita Kumaraswamy, wife of Gowda's son and former Janata Dal-Secular chief minister H.D. Kumaraswamy, lost to C.P. Yogeshwara in Channapatna, about 60 km from Bangalore.
Yogeshwara, who was a forest minister in the BJP government, quit the post and the party hoping for a Congress ticket but hopped on to SP when this was denied to him.
He defeated Anita by 6,404 votes. He polled 80,039 votes against 73,635 of Anita.
Kumaraswamy and Gowda's other son H.D. Revanna, however, won from Ramanagaram, in neighbouring Channaptna, and Holenarsipur in Gowda's home district Hassan.
Anita's defeat came as a shock to Kumaraswamy the most, apart from Gowda, as he had shifted his wife from Madhugiri in Tumkur district, from where she had won in a by-election, to Channapatna to ensure her victory.
Yogeshwar is a controversial figure - he is battling charges of cheating people by promising apartments or sites.
He was elected as a Congress candidate to the assembly in 2008 from Channapatna, switched over to the ruling Bharatiya Janata Party (BJP) only to lose the seat in a by-election.
He quit the BJP hoping for a Congress ticket this time but joined the SP bandwagon when this was denied to him.
The SP in Karnataka remains a one-man party and makes news when leaders from other parties join it at the time of election.
The only other leader who won on SP ticket from Karnataka was former chief minister S. Bangarappa, who was also a Congressman and was also in the BJP for some time.
He was elected on a BJP ticket from Shimoga in the 2004 Lok Sabha election, resigned from the party and Lok Sabha membership in 2005 and won the 2005 by-election on SP ticket.
He later quit SP and joined Congress. He has since passed away.